<?php
// +----------------------------------------------------------------------
// | ThinkPHP [ WE CAN DO IT JUST THINK ]
// +----------------------------------------------------------------------
// | Copyright (c) 2006-2016 http://thinkphp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
// +----------------------------------------------------------------------
// | Author: 流年 <liu21st@gmail.com>
// +----------------------------------------------------------------------

// 应用公共文件
function msubstr($str, $start=0, $length, $charset="utf-8", $suffix=true)
{
    if (function_exists("mb_substr")) {
        if ($suffix) {
            if ($str == mb_substr($str, $start, $length, $charset)) {
                return mb_substr($str, $start, $length, $charset);
            } else {
                return mb_substr($str, $start, $length, $charset) . "...";
            }
        } else {
            return mb_substr($str, $start, $length, $charset);
        }
    } elseif (function_exists('iconv_substr')) {
        if ($suffix) {
            if ($str == iconv_substr($str, $start, $length, $charset)) {
                return iconv_substr($str, $start, $length, $charset);
            } else {
                return iconv_substr($str, $start, $length, $charset) . "...";
            }
        } else {
            return iconv_substr($str, $start, $length, $charset);
        }
    }
    $re['utf-8'] = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|[\xe0-\xef][\x80-\xbf]{2}|[\xf0-\xff][\x80-\xbf]{3}/";
    $re['gb2312'] = "/[\x01-\x7f]|[\xb0-\xf7][\xa0-\xfe]/";
    $re['gbk'] = "/[\x01-\x7f]|[\x81-\xfe][\x40-\xfe]/";
    $re['big5'] = "/[\x01-\x7f]|[\x81-\xfe]([\x40-\x7e]|\xa1-\xfe])/";
    preg_match_all($re[$charset], $str, $match);
    $slice = join("", array_slice($match[0], $start, $length));
    if ($suffix) return $slice . "…";
    return $slice;
}